Amane Higashimiya is a wealthy alchemist consumed by the drive to avenge her late father's honor, which she believes was tarnished by Iyo Takahara, the creator of Gargoyle. To prove her family's superiority in alchemy and achieve vindication, she designed Cherub, a winged golden statue, as a direct rival to Gargoyle. This creation embodies the trope "The Only One Allowed to Defeat You," reflecting Amane's absolute insistence that Cherub must be the one to defeat Gargoyle.

Her actions stem from a deep-seated familial rivalry in alchemical craftsmanship, positioning her as a foil to Iyo Takahara. Motivated solely by restoring her father's legacy, she challenges Gargoyle and the Yoshinaga household indirectly through Cherub. This proxy rivalry defines her role as an antagonist who avoids direct confrontation.

Amane appears as a secondary character in the spin-off series *Gargoyle Alternative*. Her characterization in this storyline remains consistent with her main series portrayal, emphasizing her connection to alchemy and familial honor.